Shale
Image: <a href="//commons.wikimedia.org/wiki/User:Smith609" title="User:Smith609">Martin Smith</a> (CC BY-SA 4.0)
Mineral NameShale
Chemical FormulaVariable; primarily hydrous aluminum phyllosilicates (clay minerals) with quartz (SiO2), feldspar, and other detrital grains.
Mohs Hardness2.5
Crystal Systemamorphous
Lusterdull
Streak ColorVariable (e.g., light gray, brownish, black)
CleavageExhibits fissility, splitting along bedding planes into thin layers.
Fractureuneven
Specific Gravity2.4
Colorsyellowish-brown, gray, dark gray, black
Transparencyopaque
Type LocalityMaotianshan, Yunnan Province, China
Mineral GroupSedimentary rock (clastic)
Useshydrocarbon source rock, building material, paleontological research
Associated Mineralsclay minerals, quartz, feldspar, micas, organic matter
Raritycommon
Description
The image displays a large, tilted outcrop of layered sedimentary rock, predominantly in shades of yellowish-brown and gray, with distinct bedding planes visible across the formation.
Geological Context
Shale is a fine-grained clastic sedimentary rock formed from the compaction of mud (silt and clay) in low-energy depositional environments. The Maotianshan Shale is particularly renowned for preserving the Chengjiang Biota, a globally significant Cambrian fossil assemblage.
